Tuning Interfacial Oxygen Chemistry via Na 4 V 2 O 7 Heterostructures for Synergistic Regulation of Redox Dynamics and Structural Reversibility in Lithium‐Rich Manganese Cathodes

ABSTRACT The practical application of lithium‐rich manganese‐based oxides (LMO) cathodes is constrained by challenges such as severe capacity and voltage degradation, which results from irreversible oxygen release and migration of transition metal ions. Here, a synergistic modification strategy involving the construction of a Na 4 V 2 O 7 heterointerface layer and oxygen vacancies to enhance the oxygen redox and structural transformation reversibility of LMO. The Na 4 V 2 O 7 provides a 3D ionic transport network via VO 4 tetrahedra for Li + diffusion while stabilizing the cathode‐electrolyte interface that suppresses side reactions during cycling. Meanwhile, we innovatively employ Na 4 V 2 O 7 to achieve Li + /Na + exchange, inducing the generation of surface oxygen vacancies. The surface oxygen vacancies reduce oxygen redox activity during the initial charging process, thereby suppressing the irreversible escape of lattice oxygen while enhancing the reversibility of oxygen redox reactions and improving the stability of the oxygen framework. As a result, the modified material achieved an initial Coulombic efficiency(ICE) of 84.8%, accompanied by an augmentation in capacity retention from 58.8% to 87.1% after 200 cycles at 1 C. Furthermore, it exhibits superior rate performance and Li + kinetics. This study presents a viable strategy for enhancing the cycling stability, oxygen redox, and structural transformation reversibility of LMO, thereby advancing its practical viability.